Twitter, approaching its highly anticipated IPO, has evolved from obscure medium for geeks to influential worldwide messaging service

Other key hires came on the revenue side. Chief Financial Officer Mike Gupta, who helped take Zynga public in 2011, joined Twitter last year and will shepherd the company’s IPO. More recently, Costolo hired a former Ticketmaster CEO to develop new e-commerce programs in which advertisers might sell goods or services to users who click on sponsored tweets.

Acquisitions help

While some analysts have wondered why Twitter, which has stockpiled hundreds of millions of venture capital dollars, would opt for the headaches of going public at this point, an IPO will deliver cash for acquisitions such as Twitter’s recent purchase of mobile ad service MoPub. Costolo spent a reported $350 million on the company, which helps advertisers bid in computerized auctions to place their messages on Twitter and other mobile apps.

Analysts say the MoPub deal could be a first step toward building a broader advertising network like Google’s.

Perhaps Twitter’s greatest appeal is that it allows users to see news unfold in real time. People can follow and even communicate with newsmakers. And they can witness history.

In 2009, Twitter became an essential communication tool in Iran as the country’s government cracked down on traditional media after a disputed presidential election. Tech-savvy Iranians took to Twitter to organize protests. As the events unfolded, they used the service to send messages and pictures to the outside world. Twitter played a similar role in the 2011 Arab Spring uprisings in Egypt and other countries.

Today, a billion tweets are sent every two and a half days. To be fair, most tweets don’t comprise the world’s weightiest matters. They are ruminations about lunch, the weather and Justin Bieber — and occasionally they involve career-crashing missteps of the Anthony Weiner sort.

Mobile growth

Like Facebook, Twitter reaps most of its revenue from advertising. And it rolled out a full mobile-ad service in March 2012, about the same time as Facebook’s.

Research firm eMarketer estimates that Twitter will generate $582.8 million in worldwide ad revenue this year, up from $288.3 million in 2012.

While companies are flocking to Twitter to woo consumers, not all of them are convinced of its usefulness. More than 60 percent of U.S. marketers use Twitter, according to Forrester Research analyst Nate Elliott, but he says they are not “fully satisfied with the results.” Twitter, he says, still needs to improve the way it targets advertisements to users, and it needs to find more types of ads to sell.

Twitter’s moneymaking potential has minted the company with an estimated market value of $10 billion, based on the appraisals of venture capitalists and other early investors who have been helping to fund the business so far.

The public offering comes at a time of heightened investor interest in the IPO market. There have been 131 IPOs that have priced so far this year, according to IPO tracking firm Renaissance Capital. That’s a 44 percent increase from the same period the year before.

Wedbush Securities analyst Michael Pachter believes Twitter’s decision to tweet about the confidential filing signals the company’s intention to complete the IPO fairly quickly. “The market is hot, and the end of the year is usually is a good time to go public,” Pachter said. “I think we will get to see the documents by Halloween, and the IPO will be done by Thanksgiving.”